UPDATED 6:50PM EST -- In the midst of 48 hours of non-stop campaigning in crucial swing states, President Barack Obama said that the tightening of the race between him and Republican presidential nominee Mitt Romney doesn’t surprise him.

In an exclusive interview with NBC News’ Brian Williams, during a campaign stop in Davenport, Iowa, the president said that he never believed that the excitement surrounding his historic election four years ago and the achievement of taking out al Qaeda mastermind Osama bin Laden would inflate his likelihood of re-election.

“You guys have some short memories. Folks in your business were writing me off a year ago, saying there's no way I would win,” President Obama said. “These things go in ebbs and flows and, you know, the one thing I've tried to always be is just steady in terms of what I believe in, who I'm fighting for, and, you know, I think that one of the qualities I bring to bear in this campaign is, people see, what did I say I was going to do in 2008? And what have I delivered? And they can have some confidence that the things I say, I mean.”

Both the president and former Massachusetts Governor Romney are fiercely campaigning, criss-crossing the country in the final 13 days of the campaign.

“We always knew this was going to be a close race from the start. And what we have right now is a lead that we’ve maintained throughout the campaign and we are going to just continue to drive home the message that there are two fundamentally different choices in this election about where we take the country,” the president said.

After speaking to the crowd in Davenport, the president’s first stop in an eight-state campaign blitz, Obama sat down with Williams and discussed his relationship with Romney, his lackluster performance in the election’s first presidential debate and his administration’s handling of the crisis in Libya.

Obama defended his campaign’s release of a 20-page document detailing his plan for the next four years. The document was released the day after the final presidential debate and left pundits questioning whether its release was a late move made by a campaign that believes its opponent might be gaining momentum.

“I don’t know why you say that this is late in the game. This is exactly what I laid out at my convention,” the president told Williams. “Every point that’s in there is what we said when I accepted the Democratic nomination, is what we do to build up the middle class in this country and it’s been on our website for weeks and I hope that everybody takes an opportunity to read it, because as folks now narrow their focus on the election, in fact people here in Iowa are voting. You know, the more informed voters are and the more engaged they are about how big the stakes are, the better I think we’re going to do.”

When asked about the dynamic between he and Gov. Romney, the president said that his feelings towards Romney are no different than the feelings other presidential candidates have had before.

“I don’t think anybody would say that while you were in the middle of a campaign that you felt deep affection for the other guy, because, you know, look, you’re fighting for competing visions,” President Obama said.

From Iowa, the president traveled to Colorado and Nevada for campaign events before flying overnight to Florida to continue the second day of his battleground swing.

NBC News cameras have been granted wide-ranging access to the president as he embarks on his multi-state journey in the all-out push to appeal to voters. Clips from the president’s interview will be aired Wednesday evening on NBC Nightly News and Thursday morning on Today, with a complete behind-the-scenes profile airing Thursday night at 10pm/9c on NBC’s Rock Center with Brian Williams.